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Home >> Acura >> 1997 >> Integra GS-R, 4D Sedan >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - GS-R >> Circuit Tests >> DTC P1508: Idle Air Control (IAC) Valve Circuit Failure
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DTC P1508: Idle Air Control (IAC) Valve Circuit Failure

  1. Perform PCM reset procedure. See PCM RESET PROCEDURE/CLEARING CODES . Start engine and allow to idle for at least 30 seconds. If DTC P1508 resets, go to next step. If DTC P1508 does not reset, problem is intermittent, system is okay at this time. Check for poor connections or loose wires between IAC valve 2-pin connector and PCM 32-pin connector. See the WIRING DIAGRAMS article.
  2. Turn ignition off. Disconnect IAC valve 2-pin connector. Turn ignition on. Measure voltage between ground and IAC valve harness connector terminal No. 2 (Yellow/Black wire). If battery voltage exists, go to next step. If battery voltage does not exist, repair open in Yellow/Black wire between IAC valve harness connector and PGM-FI main relay. See the WIRING DIAGRAMS article.
  3. Turn ignition off and reconnect IAC valve 2-pin connector. Disconnect PCM 32-pin connector. See Figure. Turn ignition on. Measure voltage between ground and PCM 32-pin connector terminal No. 12 (Black/Blue wire). If battery voltage exists, go to next step. If battery voltage does not exist, repair open or short in Black/Blue wire between IAC valve 2-pin connector and PCM 32-pin connector. See the WIRING DIAGRAMS article.
  4. Using a jumper wire, momentarily connect PCM 32-pin connector terminals No. 10 (Black wire) and No. 12 (Black/Blue wire) several times. See Figure. If IAC valve does not click, replace IAC valve. If IAC valve clicks, substitute a known-good PCM and recheck. If symptom or DTC is gone, replace original PCM.
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